1. Field of the Invention
The present invention relates to temperature control devices. More particularly, the present invention relates to a thermoelectric heat exchanger that is particularly useful for converting electricity to a flow of conditioned air. The air may be heated or cooled.
2. Description of the Related Art
Modern automobile seats may be equipped with temperature control systems that allow the occupant to vary the temperature of the seat by flowing temperature-controlled air through the seat covering. One type of system comprises a seat having a heat transfer system mounted therein, such as a thermoelectric element configured to heat or cool air that is moved over the element using a separate fan unit that is also mounted within the seat. The conditioned air is distributed to the occupant by passing the air through the seat surface via a series of air ducts within the seat.
The amount of space available within, below and around the seat for such temperature control systems is severely limited. In some cars, to save weight or increase passenger room, the seats are a few inches thick and abut the adjacent structure of the car, such as the floorboard or the back of the car. Further, automobile manufacturers are increasingly mounting various devices, such as electronic components or variable lumbar supports, within, below and around the seat. Additionally, the size of the seat, particularly the seat back, needs to be as small as possible to reduce the amount of cabin space consumed by the seat.
Present temperature control systems are often too large to be mounted within, below or around vehicle seats. Conventional systems may have a squirrel cage fan five or six inches in diameter generating an air flow that passes through a duct to reach a heat exchanger that adjusts the temperature of the air. The heat exchanger is several inches wide and long, and at least an inch or so thick. From the heat exchanger the air is transported through ducts to the bottom of the seat cushion and to the back of the seat cushion. Such systems are bulky and difficult to fit underneath or inside car seats. Using thermoelectric devices to heat and cool the heat exchanger helps reduce the size of unit, but still requires a large volume for the combined heating and cooling system.
The ducting used with these systems is also bulky and difficult to use if the duct must go from a seat bottom to a seat back that is allowed to pivot or rotate. These ducts not only use additional space within the seat, but also resist air flow and thus require a larger fan to provide the air flow, and the larger fan requires additional space or else runs at greater speeds and generates more noise. Noise is undesirable inside motor vehicles. Further, the ducting affects the temperature of the passing air and either heats cool air, or cools heated air, with the result of often requiring larger fans or heat exchangers. In light of these drawbacks, there is a need for a more compact and energy efficient heating and cooling system for automobile seats, and preferably a quieter system. In addition, a more compact and energy-efficient heating and cooling system useful in seats also has uses in other localized conditioned air settings.
The present devices use air flow generators, such as fan blades, that act as both a heat exchanger to transfer a thermal differential from a thermoelectric device and thereby condition air passing over the heat exchanger, and that act as an air pump. The heat exchanger rotates and provides aerodynamic and centrifugal force to the air passing through the heat exchanger to generate pressurized air for distribution, such as to the seat of a motor vehicle.
An improved thermoelectric heat exchanger system is disclosed. The heat exchanger system has a first heat exchanger formed about an axis and configured such that fluid flows along the first heat exchanger at least partially in a first direction, and a second heat exchanger formed about the axis and configured such that fluid flows along the second heat exchanger at least partially in a direction other than the first direction. A thermoelectric device having opposing surfaces exhibits a temperature gradient between one surface and an opposing surface in response to electrical current flowing through the thermoelectric device. The one surface is in thermal communication with the first heat exchanger and the opposing surface is in thermal communication with the second heat exchanger.
Several different combinations of fluid flow directions are disclosed. For example: the first direction is at least partially outward from the axis; the first direction is at least partially perpendicular to the axis; the second direction is at least partially along the axis, while the first direction is generally outward or away from the axis; the first direction is at least partially at an angle from the axis, and the second direction is at least partially at an angle from the axis; the first direction is at least partially along the axis, and the second direction is at least partially at an angle from the axis.
In one embodiment, a heat transfer member is in thermal communication with the one or the opposing surface of the thermoelectric device and in thermal communication with the first or second heat exchanger. Another heat transfer member may also be provided in thermal communication with the other surface and with the other heat exchanger.
At least one of the first and second heat exchangers may be formed in segments to provide thermal isolation in the direction of flow. The heat transfer members may also be formed in segments to provide thermal isolation in the direction of flow, where one or more heat transfer members are used. Where the heat exchanger is made from a plurality of blades, thermal isolation may be provided by spaces in the blades in the direction of flow.
A housing containing at least one of the first and the second heat exchangers may be use to form an outlet through which air exits after passing through the at least one of the first or second heat exchangers. An auxiliary fan may also be used in conjunction with the heat exchangers. In certain configurations, the heat exchangers themselves generate fluid flow. These configurations may also use the auxiliary fan to augment the flow. The auxiliary fan may also be used as the primary or only fluid flow generator.
A thermoelectric heat exchanger system is also disclosed that has a thermoelectric device configured to generate a thermal gradient between a first temperature side and a second temperature side in response to an electrical current with at least one first heat exchanger in thermal communication with the first or the second temperature side of the thermoelectric device, wherein the heat exchanger is rotatable about a rotational axis. In this embodiment, an auxiliary fan is configured to rotate about the rotational axis and to generate fluid flow along the heat exchanger. In one embodiment, the first heat exchanger may be oriented such that fluid flow from the auxiliary fan flows through the heat exchanger along the rotational axis.
A second heat exchanger may also be provided configured to generate a fluid flow in a first direction away from the rotational axis with rotation about the rotational axis. In such case, the first heat exchanger is preferably oriented such that fluid flow generated by the auxiliary fan flows through the first heat exchanger in a second direction other than the first direction. Advantageously, the heat exchanger is constructed to provide thermal isolation in the direction of flow, such as with segments in blades or the like.
Another heat exchanger system is disclosed wherein a thermoelectric device formed about an axis and has opposing surfaces that generate a temperature gradient between one surface and an opposing surface in response to electrical current flowing through the thermoelectric device. In this heat exchanger system, first and second heat exchangers are formed about the axis and configured such that fluid flows along the first heat exchanger and along the second heat exchanger generally away from the axis. The first heat exchanger is in thermal communication with the one surface, and the second heat exchanger is in thermal communication with the opposing surface. At least one of the first and second heat exchangers is formed to provide thermal isolation in the direction of fluid flow between a plurality of portions of the at least one heat exchanger.
This configuration can be constructed such that the heat exchangers and thermoelectric device rotate about the axis during operation, at least one of the heat exchangers operating to induce fluid flow through the heat exchangers. Alternatively, the heat exchangers and thermoelectric device are stationary, but an auxiliary fan rotates about the axis and causes fluid to flow along at least one of the first and second heat exchangers. In one preferred embodiment of this system, at least one of the first and second heat exchangers is formed in segments to provide the thermal isolation.
Yet another thermoelectric heat exchanger system is disclosed with a thermoelectric device formed about an axis and having opposing surfaces that generate a temperature gradient between one surface and an opposing surface in response to electrical current flowing through the thermoelectric device. First and second heat exchangers are about the axis and configured such that fluid flows along the first heat exchanger and along the second heat exchanger generally away from the axis. The first heat exchanger is in thermal communication with the one surface, and the second heat exchanger is in thermal communication with the opposing surface. An auxiliary fan rotates about the axis and generates fluid flow along at least one of the first and second heat exchangers. Preferably, at least one of the first and second heat exchangers is formed to provide the thermal isolation in the direction of flow, such as through construction in a plurality of substantially thermally isolated segments.
A method of conditioning a fluid flow is also contemplated which involves the steps of flowing current through a thermoelectric device having opposing surfaces to generate a temperature gradient between a first surface and a second surface of the thermoelectric device, flowing a fluid along a first heat exchanger formed about an axis at least partially in a first direction, the first heat exchanger in thermal communication with the first surface, and flowing a fluid along a second heat exchanger formed about the axis at least partially in a direction other than the first direction, the second heat exchanger in thermal communication with the second surface.
The direction may be in any reasonable configuration, such as, but not limited to: the first direction is at least partially outward from the axis; the first direction is at least partially perpendicular to the axis; the second direction is at least partially along the axis; the first direction is at least partially at an angle from the axis, and the second direction is at least partially at an angle from the axis and; the first direction is at least partially along the axis, and the second direction is at least partially at an angle from the axis.
Advantageously, the method further involves forming at least one of the first and second heat exchangers to provide thermal isolation in the direction of flow, such as forming the heat exchangers in segments. The flowing of fluid may be provided by an auxiliary fan that rotates about the axis. In addition, or alternatively, the flowing of fluid may be provided by the first or second heat exchanger rotating about the axis.
Yet another method is disclosed, involving the steps of flowing current through a thermoelectric device having opposing surfaces to generate a temperature gradient between a first surface and a second surface of the thermoelectric device, flowing a fluid along a first heat exchanger formed and rotational about an axis, the first heat exchanger in thermal communication with the first surface. The flowing is at least partially provided via an auxiliary fan configured to rotate about the axis and to generate fluid flow along the first heat exchanger. In one embodiment, the first heat exchanger is oriented such that fluid from the auxiliary fan flows through the heat exchanger along the rotational axis. Generating fluid flow along a second heat exchanger in a direction away from the rotational axis with rotation about the rotational axis may also be provided. The second heat exchanger may at least partially generate the fluid flow along the second heat exchanger. The method may also involve thermally isolating portions or segments of the heat exchanger in the direction of fluid flow.
Another method of conditioning flowing fluid involves the steps of generating a temperature gradient in a thermoelectric device between one surface and an opposing surface and flowing fluid along first and second heat exchangers formed about an axis and configured such that the fluid flows along the first heat exchanger and along the second heat exchanger generally away from the axis, the first heat exchanger in thermal communication with the one surface, and the second heat exchanger in thermal communication with the opposing surface. At least one of the first and second heat exchangers is formed to provide thermal isolation in the direction of fluid flow, such as by using a plurality of segments to form the at least one heat exchanger.
The method may further involve rotating the heat exchangers and thermoelectric device about the axis during operation, the heat exchangers operating to induce fluid flow through the heat exchangers. The heat exchangers and thermoelectric device may also be stationary, wherein fluid flow is generated along at least one of the first and second heat exchangers by rotating an auxiliary fan about the axis.
These and other features are disclosed in further detail below.